So... when can I expect these Verses to balance out?

[MarioDaems]

That’s what you would think initially, but check this for the explanation:

Why one of the music sheets is severely lacking?

[score] As shown in the picture, music sheet #1 is more than doubled the number of music sheet #4. WHY?? I know some others lacks sheets other than #4, it varies among players. It cannot be a programming error since implementing a uniform distribition is the easiest thing (easier than a non-uniform like it is now). So why? Is this some kind of psychological trick on gamers that I do not know?